INTERIM CONSTRUCTION RECORD REPORT TAILINGS POND 4 STAGE 3 RAISE

Transcription

1 # West Georgia St. Vancouver, BC V6E 4A2 Ph: (604) Fax: (604) INTERIM CONSTRUCTION RECORD REPORT TAILINGS POND 4 STAGE 3 RAISE OCTOBER 2009 NORTH AMERICAN TUNGSTEN CORPORATION LTD. CANTUNG MINE, NT P.O. BOX 848 WATSON LAKE, YT YOA 1C0 P: F:

2 Tailings Pond 4 Interim Construction Record Report ii EXECUTIVE SUMMARY The tailings management plan at, NT, calls for tailings deposition in Tailings Pond 4 through the remaining life of the mine, including future production following the current temporary mine shutdown. This requires raising the Tailings Pond 4 containment berm to provide sufficient storage capacity in the pond. The pond will be raised in three stages to a final elevation of ft. Stage 1 of the containment berm raise was undertaken in 2007, Stage 2 was undertaken in 2008, and the partial Stage 3 construction was undertaken in The partial Stage 3 raise construction occurred from July 15, 2009 to August 10, The current berm construction included that required to provide the necessary foundation width to enable future completion of the Stage 3 construction, while accounting for current mine operations. The 2009 construction included upstream construction of a 10 ft wide zone of 75 mm material and a 25 ft wide zone of waste rock encapsulated with geotextile, which was capped with 300 mm material along the length of the dam and to an elevation of approximately 3730 ft, which matched the existing dam. In addition, the upstream face of the new construction slope was covered with a layer of geotextile. Jedway enterprises Ltd. (Jedway) was contracted to complete the partial Stage 3 construction. Survey services were provided by North American Tungsten Corporation Ltd. (NATCL) and EBA Engineering Consultants Ltd. (EBA) provided quality control throughout construction. The partial Stage 3 raise to Tailings Pond 4 was generally constructed in accordance with the design; however, the required deviations in design to accommodate site-specific conditions include: Raising all material in the design by 2.5 ft to accommodate the higher tailings beach elevation. Flattening of the upstream slope from the original design of 1.8:H:1V to 2H:1V to maintain the designed final crest width of 30 ft at an elevation of ft. PO Box 848, Watson Lake, YT, Y0A 1C0 P: , F:

3 Tailings Pond 4 Interim Construction Record Report iii TABLE OF CONTENTS PO Box 848, Watson Lake, YT, Y0A 1C0 P: , F: PAGE 1.0 INTRODUCTION GENERAL SCOPE OF WORK PROJECT DETAILS DEVIATIONS FROM DESIGN TAILINGS BREACH ELEVATION HIGHER THAN DESIGN UPSTREAM SLOPE FLATTENED FROM 1.8H:1V TO 2H:1V CONSTRUCTION MATERIALS MM MATERIAL WASTE ROCK MATERIAL MM MATERIAL GEOTEXTILE CONSTRUCTION ACTIVITIES GENERAL CONSTRUCTION EQUIPMENT SURVEY CONTROL MATERIAL PLACEMENT MM MATERIAL WASTE ROCK MM MATERIAL GEOTEXTILE DAM CREST SURFACE DRAINAGE SETTLEMENT MONUMENTS INSTRUMENTATION MATERIAL QUANTITIES SURVEY DATA QUALITY ASSURANCE PARTICLE SIZE ANALYSIS MOISTURE-DENSITY RELATIONSHIP MONITORING GENERAL PIEZOMETERS 9

4 Tailings Pond 4 Interim Construction Record Report iv 8.3. EMBANKMENT MONITORING PROGRAM SETTLEMENT SURVEY ANNUAL INSPECTIONS CLOSURE REFERENCES 12 FIGURES & PHOTOGRAPHS 13 APPENDIX B TAILS POND 4 AS BUILT DRAWING 22 PO Box 848, Watson Lake, YT, Y0A 1C0 P: , F:

5 Tailings Pond 4 Interim Construction Record Report INTRODUCTION 1.1. GENERAL Construction of Tailings Pond 4 during the summer of 2009 was conducted by North American Tungsten Corporation Ltd. (NATCL) and is based on the design report entitled Design Report for the Stage 2 and 3 Raises of the Containment Berm for Tailings Pond 4 issued March 2008 by EBA Engineering Consultants Ltd. (EBA, 2008). NATCL received approval from the Mackenzie Valley Land and Water Board for dam construction to an elevation of ft as described in the letter dated April 8, 2009 (MVLWB a, 2009). The construction was carried out between July 15 and August 10 as a partial completion of the proposed Stage 3 raise to Tailings Pond 4. The 2009 construction included upstream construction of a 10 ft wide zone of 75 mm material and a 25 ft wide zone of waste rock encapsulated with geotextile, which was capped with 300 mm material along the length of the dam and to an elevation that matched the existing dam. In addition, the upstream face of the new construction slope was covered with a layer of geotextile. On June 29, 2009, NATCL announced the temporary suspension of operations at the site, effective October 15, Consequently, the scheduled Stage 3 raise construction was reduced to include only what was necessary to provide sufficient capacity to operate until October 15, 2009 and to prepare the dam for future completion of the berm to a crest elevation of ft. The length of the mine shutdown is not known; however, NATCL is optimistic that economic and market conditions will improve sufficiently so that operations can resume in The Short Term Closure Plan (NATCL, 2009), submitted to MVLWB in August 2009, includes the shutdown and startup strategies to be followed for tailings pond operations and future construction following the shutdown. This report is an interim construction record report and is limited to an overview of construction that occurred from July 15, 2009 to August 10, 2009 on Tailing Pond 4. The construction supervisor, a representative of NATCL, documented all observations. Select construction photographs are referenced throughout the report where applicable. Imperial units have been used in parts of this report in keeping with standards.

6 Tailings Pond 4 Interim Construction Record Report SCOPE OF WORK A representative from EBA was present on site from July 21, 2009 to August 9, 2009 to observe the completion of the 2009 Tailings Pond 4 construction. Throughout the construction of Tailings Pond 4, EBA s role was as follows: Observe the contractor s material placement techniques. Complete quality control testing of the granular materials, which included particle size analysis and moisture-density relationship testing. Monitor placement and compaction of the waste rock material. Inspect geotextile installation. Throughout the construction of Tailings Pond 4, NATCL s role was as follows: Ensure that proper materials, including granular material and geotextile, were available for construction. Monitor construction to ensure dam is constructed to the design intent. Complete construction surveys and quantity surveys. 2.0 PROJECT DETAILS, operated by North American Tungsten Corporation Ltd., is located approximately 310 km northeast of Watson Lake, YT in western Northwest Territories. The mine site is accessible by road through the Yukon via Highway 4 (Robert Campbell Highway) and Highway 10 (Nahanni Range Road). A general site overview is presented in Figure 1. There are four tailings containment structures and one water management structure at, as shown in Figure 1. Tailings Ponds 1 and 2 are presently decommissioned and Tailings Pond 3 is at design capacity. In accordance with the updated Tailings Management Plan completed by EBA for NATCL (EBA, 2009) and submitted to MVLWB on July 7, 2009, Tailings Pond 4 is currently used for tailings deposition and Tailings Pond 5 is used as a water exfiltration pond. The 2009 partial construction of the Stage 3 raise to Tailings Pond 4 was required to provide the necessary foundation width to enable future completion of the containment berm to the design elevation of ft. Tailings Pond 4 prior to the 2009 construction is presented in Photograph 1.

7 Tailings Pond 4 Interim Construction Record Report DEVIATION FROM DESIGN The full Stage 3 raise to Tailings Pond 4 was not completed during the 2009 construction season. The construction was limited to necessary material placement on Tailings Pond 4 to allow for future construction to a final elevation of ft. Deviations from the design are detailed below TAILINGS BEACH ELEVATION HIGHER THAN DESIGN In the Tailings Pond 4 design report (EBA, 2008) it was estimated that the upstream tailings elevation would be at 3721 ft, however, immediately prior to construction the tailings beach elevation ranged between 3723 ft and ft. To accommodate the higher tailings beach elevation, the design was adjusted by raising all materials in the design by 2.5 ft. Consequently, the overlying 300 mm crest material, to be constructed in the future, required a 2.5 ft decrease in layer thickness to maintain a final design elevation of ft for the Stage 3 raise UPSTREAM SLOPE FLATTENED FROM 1.8H:1V TO 2H:1V At the request of EBA, the upstream slope of the containment berm was flattened from 1.8H:1V to 2H:1V. This was achieved by offsetting the toe of the berm raise further into the tailings pond in order to maintain the designed final crest width of 30 ft at the elevation of ft. 4.0 CONSTRUCTION MATERIALS MM MATERIAL The 75 mm minus material used in construction was mainly sourced from a stockpile located on the east side of the airstrip. The airstrip stockpile had been screened in 2008 to remove material larger than 75 mm. The balance of the 75 mm material was sourced from a stockpile at the Ski Hill burrow that had also been screened in The 75 mm material is well-graded sand and gravel with a maximum particle size of 75 mm. In total, approximately 92,272 ft 3 (2,613 m 3 ) of the 75 mm material was used for the Tailings Pond 4 Stage 3 partial raise.

8 Tailings Pond 4 Interim Construction Record Report WASTE ROCK MATERIAL The waste rock material used in construction was sourced from the non-acid generating waste rock pile across from and east of the mine portal (see Photograph 2). The waste rock used in construction has a maximum particle size of 700 mm and a nominal size of 300 mm to 500 mm. A sample of the material was tested for carbon, sulphur, and tungsten every 500 tons during placement to assess the acid generating potential. Approximately 121,509 ft 3 (3441 m 3 ) of waste rock was sourced from the non-acid generating stockpile for the Tailings Pond 4 Stage 3 partial raise MM MATERIAL The 300 mm minus material used in construction was sourced from the stockpile just north of Tailings Pond 4 (see Photograph 3). The 300 mm material stockpile was originally sourced from the Ski Hill burrow area but relocated to its present location in The material is well-graded granular material with a maximum particle size of 300 mm. Particles in the stockpile larger than 300 mm were removed with the excavator. Approximately 23,501 ft 3 (665 m 3 ) of the 300 mm material was used for the Tailings Pond 4 Stage 3 partial raise GEOTEXTILE Two types of geotextile were used during construction on Tailings Pond 4, LP8 nonwoven geotextile and LP16 nonwoven geotextile. Layfield Environmental Services Ltd supplied all geotextile used in construction. 5.0 CONSTRUCTION ACTIVITIES 5.1. GENERAL Jedway Enterprises Ltd. (Jedway) of Watson Lake, YT was contracted by NATCL to construct the partial Stage 3 Tailings Pond 4 raise. Construction commenced on July 15, 2009 and was completed on August 10, The partial raise comprised placement of the upstream berm raise to ± 1.0 ft. The construction extended throughout the length of the dam, from Sta ft to Sta ft. Prior to construction, the tailings beach elevation ranged between 3723 ft and ft.

9 Tailings Pond 4 Interim Construction Record Report 5 The 2009 partial construction of the Stage 3 raise included: A 10 ft wide zone of 75 mm material against the existing upstream slope to an elevation of ± 0.4 ft at crest and ± 1 ft at the centre. A 25 ft wide zone of waste rock material to an elevation of ± 0.6 ft at the crest and ± 0.6 ft at the centre, which was encapsulated with LP16 geotextile and placed upstream of the 75 mm material. A 0.5 ft to 1 ft thick layer of 300 mm material placed across the 25 ft wide zone of encapsulated waste rock from an elevation of ± 0.5 ft at the crest and ± 0.4 ft at the centre, which tied into the adjacent 75 mm material crest. A 2H:1V upstream slope. A shallow inward slope of 4% along the dam crest for inward surface drainage CONSTRUCTION EQUIPMENT Jedway Enterprises Ltd. mobilized the following equipment to site by July 15, 2009 to complete construction on Tailings Pond 4: 1 Caterpillar 345 Excavator 1 D400D 40 Ton Rock Truck 1 A35 Volvo Rock Truck 1 Caterpillar 972G Loader 1 Caterpillar D6H 1 Caterpillar Packer In addition, Jedway Enterprises Ltd. utilized the following equipment which was already present at the mine site: 1 Link Belt 3400 Excavator 1 Caterpillar 330 Excavator 1 D400D 40 Ton Rock Trucks 1 Caterpillar D8R 1 Caterpillar 966G Loader 5.3. SURVEY CONTROL NATCL provided Jedway with surveying control during construction. Surveyors were onsite to complete construction surveys, quantity surveys, and to provide other assistance as required. The quantity survey was recorded for the production of a final quantity report supplied to Jedway. NATCL was responsible for completing the surveys and compiling the survey data used to produce the final as-built drawings.

10 Tailings Pond 4 Interim Construction Record Report MATERIAL PLACEMENT To gain access to Tailings Pond 4, a road was constructed in the bank northwest of the pond. The access road was constructed using waste rock material sourced from the nonacid generating mine waste rock stockpile MM MATERIAL Tailings Pond 4 Stage 3 construction commenced with a key-in to Tailings Pond 3 in preparation for placing 75 mm minus material (see Photograph 4). Waste rock was pushed into the tailings beach across the length of the dam and subsequently covered with a thin layer of 75 mm material and a layer of LP8 geotextile to create a solid foundation (see Photograph 5). The placement of the 75 mm material followed in 1 ft lifts from a base elevation of ± 0.3 ft to tie in with the existing upstream crest of the dam, at an elevation of ± 1.0 ft, from Sta ft to Sta ft. Each lift was compacted with multiple passes of the vibratory drum roller (see Photograph 6) and an upstream slope of 2H:1V was maintained. The width of the filter zone is 9.3 to 13.8 ft. EBA completed quality control testing of the 75 mm filter zone. Refer to Photograph 7 for complete placement of the 75 mm filter zone WASTE ROCK As detailed in the design report (EBA, 2008), waste rock placement followed placement of the 75 mm filter zone. LP16 geotextile was rolled out perpendicular to the dam from Sta ft to Sta ft, followed by placement of the waste rock in 1.5 to 2 ft lifts (see Photograph 8). The waste rock was placed against the upstream slope and inwards towards the centre of the tailings pond. In areas where softer tailings were encountered, a layer of waste rock was compacted into the tailings beach until a firm foundation was achieved. Thereafter, construction continued as per the design. Each 1.5 ft to 2 ft lift was compacted with multiple passes of the D6H Cat until no deflection was observed (see Photograph 9). The upstream waste rock slope was sloped to 2H:1V (see Photograph 10). The final elevation of the waste rock is ± 0.6 ft at the crest and ± 0.6 ft at the centre. Following waste rock placement, the geotextile was wrapped to enclose the waste rock. A 2 ft minimum overlap was maintained along the transverse axis, while a 4 to 5 ft overlap was maintained along the longitudinal axis. At both ends of the dam, the geotextile was rolled up to completely encapsulate the waste rock. The width of the

11 Tailings Pond 4 Interim Construction Record Report 7 waste rock zone is 20.7 ft to 28.7 ft. EBA monitored the material placement and compaction. Photograph 11 shows the encapsulated waste rock MM MATERIAL Following construction of the waste rock zone, a 300 mm material cap was placed to protect the geotextile from damage (see Photograph 12). A 0.5 ft to 1 ft lift was placed across the waste rock zone to a final elevation of ± 0.5 ft at the crest and ± 0.4 ft at the centre. The variance in final elevation is due to a 4% inward slope across the dam crest. The material was compacted with multiple passes of the vibratory drum roller. The 300 mm material crest tied into the crest of the 75 mm filter zone, while the upstream slope of the 300 mm material blended into the 2H:1V slope of the underlying waste rock. The width of the 300 mm cap is 20.7 ft to 28.7 ft GEOTEXTILE After material placement on Tailings Pond 4, LP8 geotextile was placed on the upstream slope, perpendicular to the length of the dam. The geotextile extended 10 ft onto the tailings beach from the toe of the upstream slope and 10 ft onto the 300 mm cap from the surface of the upstream slope. On the surface of the dam, wooden stakes secured the geotextile. Rounded boulders were placed on the seams and at the toe of the geotextile along the upstream slope and on the tailings beach to secure the geotextile, as shown in Photograph DAM CREST SURFACE DRAINAGE The elevation of the dam surface on the upstream slope is ± 0.5 ft. The elevation of the dam surface on the downstream slope is ± 0.9 ft. The difference in elevation of the dam surface at the upstream and downstream slopes is due to the shallow inward slope for surface drainage. An inward slope of 4% was maintained across the crest of Tailings Pond 4 to manage surface drainage into the tailings pond. The shallow slope extends across the entire dam crest, including the recently placed 75 mm filter zone and 300 mm cap material. Low areas detected across Tailings Pond 4 where filled with the appropriate material (see Photograph 14).

12 Tailings Pond 4 Interim Construction Record Report SETTLEMENT MONUMENTS After the partial Stage 3 raise was completed on Tailings Pond 4, two settlement monuments were installed to monitor future vertical movement of the containment berm. The monuments were installed at Sta ft and Sta The settlement monuments are anchored into the 75 mm filter material and their locations were surveyed INSTRUMENTATION Vibrating wire piezometers were installed in Boreholes TP4-07-BH01, TP4-07-BH2, TP4-07-BH03, TP4-07-BH04, TP4-07-BH05, and TP4-07-BH06 in the existing Tailings Pond 4 berm during the April 2007 geotechnical investigation. On June 17, 2008, an additional vibrating wire piezometer was installed 6 ft (1.8 m) beneath the waste rock foundation at Sta and at an approximate elevation of ft. The wiring for the piezometers was extended during the berm raise in 2008 to allow for continued pore pressure measurement during and after construction. No additional piezometers were installed in MATERIAL QUANTITIES 6.1. SURVEY DATA A Leica TCR 705 Total Station was used by NATCL personnel to complete the required surveys on Tailings Pond 4. Further, the CAD program Promine was used to calculate material quantities and complete final as-built drawings. The completed partial Stage 3 construction is shown in Photograph 15. The total volume of material placed on Tailings Pond 4 was 237,281 ft 3 (6,719 m 3 ) during 2009 construction. This volume includes the 75 mm material, waste rock, and 300 mm material and includes the estimated amount of material pushed into the tailings to create a solid foundation in the tailings. A breakdown of the calculated quantities for each material type is shown in Table 1. TABLE 1: Construction Quantities for Tailings Pond 4 Material Imperial Volume (ft 3 ) Metric Volume (m 3 ) 75 mm 92,272 2, mm 121,509 3,441 Waste Rock 23, Total Volume Placed in ,281 6,719

13 Tailings Pond 4 Interim Construction Record Report QUALITY ASSURANCE Quality control testing of the 75mm and 300mm material was provided by EBA during construction. The information relating to the quality control testing will be presented by EBA in a separate report PARTICLE SIZE ANALYSIS Particle size analysis completed by EBA was conducted on 75 mm and 300 mm material samples during construction MOISURE-DENSITY RELATIONSHIP Moisture-density relationship testing by EBA was conducted on both 75 mm and 300 mm materials during construction. 8.0 MONITORING 8.1. GENERAL Performance monitoring is an integral part of the design, construction, and operation of any water or tailings containment structure. Monitoring of the berm serves the following functions: Monitor groundwater level within the new embankment. Monitor movements of the berm. Monitor groundwater quality downstream. Satisfy regulatory requirements for berm performance. A monitoring program is currently in effect at. Measurements and observations are recorded on a regular basis by NATCL and reviewed by EBA to assess berm performance and to identify maintenance requirements PIEZOMETERS The vibrating wire piezometers installed during the geotechnical investigation in April 2007 shall be sufficient to monitor variations of the local physical groundwater conditions.

14 Tailings Pond 4 Interim Construction Record Report EMBANKMENT MONITORING PROGRAM Observations during the geophysical investigation in April 2007 and Stage 1 construction in the fall of 2007 indicate that buried waste exists under Tailings Pond 4 berm. There is a risk that some berm movement may be experienced as a result of the underlying industrial waste shifting or consolidating. In November 2007, six inclinometers and six additional piezometers were installed along the berm length on the downstream slope to monitor and evaluate future berm movement. The inclinometers, in combination with the piezometers, shall provide a means of monitoring berm performance SETTLEMENT SURVEY Permanent settlement survey monitoring points shall be established once the berm reaches the final design elevation of ft, to monitor long term vertical movement in the structure. Temporary settlement monitoring points were established at 2 locations on the upstream crest of the berm in the 75 mm material following the partial Stage 3 raise construction. The settlement monuments are located at Sta ft and Sta ft and shall be used to monitor short term vertical movement. The temporary settlement monuments shall be removed prior to the completion of the Stage 3 berm raise ANNUAL INSPECTIONS In compliance with the water license, License No. MV2002L2-0019, issued to NATCL by the Mackenzie Valley Land and Water Board on January 30, 2009, an inspection of the tailings containment area shall be carried out annually during the summer season by a Geotechnical Engineer (MVLWB b, 2009, Section E.3.e). It will be necessary for the Geotechnical Engineer to conduct visual inspections for signs of instability, such as deformations, slumping, or transversal cracks. Specific tasks conducted during the inspection will include the following: Inspection of the upstream and downstream slopes for signs of distress. Inspection of the berm crest for signs of transverse cracking. Inspection of the abutments and downstream toe for any evidence of seepage. Review of deformation and piezometer data to verify conformance with design assumptions. In addition, the water license requires that an independent dam safety review be completed prior to September 30, 2010 and shall be carried out every five years until expiry of the license (MVLWB b, 2009, Section E.3.d).

15 Tailings Pond 4 Interim Construction Record Report CLOSURE This report is an account of the construction activities completed in 2009 for the Tailings Pond 4 partial Stage 3 construction and has been prepared by Tessa Brinkman, Junior Mine Engineer of NATCL for. Please do not hesitate to contact the Environmental Department at with any questions or concerns pertaining to the report. Tessa Brinkman Junior Mine Engineer site, North American Tungsten Corp.

16 Tailings Pond 4 Interim Construction Record Report REFERENCES North American Tungsten Corporation Ltd. (NATCL). (2009, August). Care and Maintenance Plan for Short Term Closure Commencing October Tungsten, NT. EBA Engineering Consultants Ltd. (EBA). (2009, July) Tailings Monitoring Plan, NT. Edmonton, AB. Mackenzie Valley Land and Water Board (MVLWB a). (2009, April 8). Request to raise Tailings Pond 4: Mining and Milling. Yellowknife, NT. Mackenzie Valley Land and Water Board (MVLWB b). (2009, January 30). Mackenzie Valley Land and Water Board Water License (License No. MV2002L2-0019). Yellowknife, NT: Section E.3. EBA Engineering Consultants Ltd. (EBA). (2008, March). Design Report for the Stage 2 and 3 Raises of the Containment Berm for Tailings Pond 4 Cantung Mine, Tungsten, NT. Whitehorse, YT.

17 Tailings Pond 4 Interim Construction Record Report 13 FIGURE 1:, NT Site Plan

18 Tailings Pond 4 Interim Construction Record Report 14 PHOTOGRAPH 1: Tailings Pond 4 Prior to 2009 Construction PHOTOGRAPH 2: Waste Rock Stockpile Located East of the Mine Portal

19 Tailings Pond 4 Interim Construction Record Report 15 PHOTOGRAPH 3: 300 mm Material Stockpile Located Adjacent to Tailings Pond 4 PHOTOGRAPH 4: Key-in to Tailings Pond 3

20 Tailings Pond 4 Interim Construction Record Report 16 PHOTOGRAPH 5: Foundation Preparation for the 75 mm Filter Zone PHOTOGRAPH 6: 75mm Filter Zone being Compacted with the Vibratory Drum Roller

21 Tailings Pond 4 Interim Construction Record Report 17 PHOTOGRAPH 7: Completed Placement of the 75 mm Filter Zone PHOTOGRAPH 8: Initial Waste Rock Placement

22 Tailings Pond 4 Interim Construction Record Report 18 PHOTOGRAPH 9: Waste Rock Lifts are Graded and Compacted with the Cat PHOTOGRAPH 10: Upstream Slope of Waste Rock is Sloped 2H:1V

23 Tailings Pond 4 Interim Construction Record Report 19 PHOTOGRAPH 11: Waste Rock Zone Encapsulated with Geotextile PHOTOGRAPH 12: Placement of the 300 mm Material Cap to Protect the Underlying Geotextile

24 Tailings Pond 4 Interim Construction Record Report 20 PHOTOGRAPH 13: Geotextile Wrapped Around Wood and Boulders to Secure the Geotextile PHOTOGRAPH 14: Filling and Compacting Low Spots on Tailings Pond 4

25 Tailings Pond 4 Interim Construction Record Report 21 PHOTOGRAPH 15: End of 2009 Construction for Tailings Pond 4

26 Tailings Pond 4 Interim Construction Record Report 22 INTERIM CONSTRUCTION RECORD REPORT TAILINGS POND 4 STAGE 3 RAISE OCTOBER 2009 APPENDIX A TAILS POND 4 AS BUILT DRAWING

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